Emile Heskey is carried off with concussion during Aston Villa's Peace Cup match with Malaga which the Spanish side won 1-0 on Saturday night. Photograph: Denis Doyle/Getty Images

Curtis Davies believes that Aston Villa face a "tough" season ahead unless Martin O'Neill can bring in some stellar signings before the new campaign gets under way. The central defender, who admitted there is little depth to the current Villa squad, is keen to see O'Neill add several "top-quality" players over the coming weeks to maintain the progress that has established the club in the Premier League's top six over the past two years.

Villa used fewer players in the Premier League last season than any other club, and since then Martin Laursen, Gareth Barry and Zat Knight have all departed, with only Stewart Downing arriving in the opposite direction. Downing, however, will not be fit until December, leaving O'Neill effectively three players down from the end of last term, when he admitted Villa did not have the personnel to cope with the demands of competing at home and in Europe.

Davies remains confident that the Villa manager, who made a flurry of signings on the eve of last season, will make a number of acquisitions before the first Premier League game against Wigan Athletic in a little under three weeks' time - Jermaine Jenas and Sylvain Distin are both targets - though he acknowledged that there is a need for quality as well as quantity if the club have serious ambitions.

"It would give us a lift to see a couple of new faces come in but at the same time they need to be quality And that's what the manager wants. You can sign players for depth but the type of player we want to move us forward needs to be top quality, the likes of Stewart Downing. Hopefully, we can make some more signings near Downing's quality and then I'm sure we'll be fine come the start of the season."

Villa's shortcomings were highlighted during the 1–0 defeat to Malaga in the Peace Cup on Saturday night, when the early loss of Emile Heskey with mild concussion further stretched O'Neill's limited options. Gabriel Agbonlahor, James Milner and Craig Gardner were all absent after being given an extended break following their involvement with England Under-21s last month but Davies knows that the return of that trio will not be enough.

"The squad is thin," the 24-year-old added. "And even with the squad we put out against Malaga a couple have got injured. It is difficult but I am sure that the manager, behind the scenes, is trying to get things done. We lost Zat [Knight] this week to Bolton but obviously the gaffer is looking to strengthen.

"Once we get the Under-21 lads back in, I don't think you will notice it so much with the first XI. But after the first XI, you are looking at a lot of young lads who haven't played much at any level, let alone Premier League or Uefa Cup, so it is going to be tough. But the manager is shrewd, and hopefully we can get a few people in so that they can get settled into the squad before the season, rather than trying to bed them in before things have already started."Davies is eager to continue his own development over the last two years, during which time his performances have caught the eye of Fabio Capello, the England manager. The former West Bromwich Albion defender, who has been called up to the England squad on a couple of occasions, would love to win his first senior cap next season and be on the plane to South Africa for the World Cup but he claims that the latter is far from his mind at the moment.

"I've got no right to even think about that [the World Cup in South Africa]," he said. "I would love to go there. I'm not going to lie; it's my dream to play for England, and especially to go to the World Cup. But, at the same time, there are centre-halves in there already who are holding the places and there are so many on the fringes, so I need to be at the top of the fringe group and then hopefully be pushing for the full squad."

Sign up for the Guardian Today

Our editors' picks for the day's top news and commentary delivered to your inbox each morning.